* Side effects:
 *	The err field of the currently operative State is set
 *	  to a string describing the SSL negotiation failure reason
 *
 *-------------------------------------------------------------------
 */
static int
VerifyCallback(int ok, X509_STORE_CTX *ctx)
{
    Tcl_Obj *cmdPtr;
    SSL   *ssl		= (SSL*)X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx());
    X509  *cert		= X509_STORE_CTX_get_current_cert(ctx);
    State *statePtr	= (State*)SSL_get_app_data(ssl);
    Tcl_Interp *interp	= statePtr->interp;
    int depth		= X509_STORE_CTX_get_error_depth(ctx);
    int err		= X509_STORE_CTX_get_error(ctx);

    int ssl2 = 0, ssl3 = 0;
    int tls1 = 1, tls1_1 = 1, tls1_2 = 1, tls1_3 = 1;
    int proto = 0, level = -1;
    int verify = 0, require = 0, request = 1, post_handshake = 0;

    dprintf("Called");

#if defined(NO_TLS1) || defined(OPENSSL_NO_TLS1) || defined(OPENSSL_NO_TLS1_METHOD)
    tls1 = 0;
#endif
#if defined(NO_TLS1_1) || defined(OPENSSL_NO_TLS1_1) || defined(OPENSSL_NO_TLS1_1_METHOD)
    tls1_1 = 0;
#endif
#if defined(NO_TLS1_2) || defined(OPENSSL_NO_TLS1_2) || defined(OPENSSL_NO_TLS1_2_METHOD)
    tls1_2 = 0;
#endif
#if defined(NO_TLS1_3) || defined(OPENSSL_NO_TLS1_3)
    tls1_3 = 0;
#endif

    if (objc < 2) {

		    "\": not a TLS channel", (char *)NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "CHANNEL", "INVALID", (char *)NULL);
	    Tls_Free((void *)statePtr);
	    return TCL_ERROR;
	}
	ctx = ((State *)Tcl_GetChannelInstanceData(chan))->ctx;
    } else {
	if ((ctx = CTX_Init(statePtr, server, proto, keyfile, certfile, key, cert, key_len,
		cert_len, CApath, CAfile, ciphers, ciphersuites, level, DHparams)) == NULL) {
	    Tls_Free((void *)statePtr);
	    return TCL_ERROR;
	}
    }

    statePtr->ctx = ctx;

    SSL_set_bio(statePtr->ssl, statePtr->p_bio, statePtr->p_bio);
    BIO_set_ssl(statePtr->bio, statePtr->ssl, BIO_NOCLOSE);

    /*
     * End of SSL Init
     */
    dprintf("Returning %s", Tcl_GetChannelName(statePtr->self));
    Tcl_SetResult(interp, (char *)Tcl_GetChannelName(statePtr->self), TCL_VOLATILE);
    return TCL_OK;
}

/*
 *-------------------------------------------------------------------
 *
 * UnimportObjCmd --

    /* Make sure to operate on the topmost channel */
    chan = Tcl_GetTopChannel(chan);

    if (Tcl_GetChannelType(chan) != Tls_ChannelType()) {
	Tcl_AppendResult(interp, "bad channel \"", Tcl_GetChannelName(chan),
		"\": not a TLS channel", (char *)NULL);
	Tcl_SetErrorCode(interp, "TLS", "UNIMPORT", "CHANNEL", "INVALID", (char *)NULL);
	return TCL_ERROR;
    }

    if (Tcl_UnstackChannel(interp, chan) == TCL_ERROR) {
	return TCL_ERROR;
    }

	Tcl_AppendResult(interp, "SSL2 protocol not supported", (char *)NULL);
	return NULL;
    }
    if (ENABLED(proto, TLS_PROTO_SSL3)) {
	Tcl_AppendResult(interp, "SSL3 protocol not supported", (char *)NULL);
	return NULL;
    }
#if defined(NO_TLS1) || defined(OPENSSL_NO_TLS1) || defined(OPENSSL_NO_TLS1_METHOD)
    if (ENABLED(proto, TLS_PROTO_TLS1)) {
	Tcl_AppendResult(interp, "TLS 1.0 protocol not supported", (char *)NULL);
	return NULL;
    }
#endif
#if defined(NO_TLS1_1) || defined(OPENSSL_NO_TLS1_1) || defined(OPENSSL_NO_TLS1_1_METHOD)
    if (ENABLED(proto, TLS_PROTO_TLS1_1)) {
	Tcl_AppendResult(interp, "TLS 1.1 protocol not supported", (char *)NULL);
	return NULL;
    }
#endif
#if defined(NO_TLS1_2) || defined(OPENSSL_NO_TLS1_2) || defined(OPENSSL_NO_TLS1_2_METHOD)
    if (ENABLED(proto, TLS_PROTO_TLS1_2)) {
	Tcl_AppendResult(interp, "TLS 1.2 protocol not supported", (char *)NULL);
	return NULL;
    }
#endif
#if defined(NO_TLS1_3) || defined(OPENSSL_NO_TLS1_3)
    if (ENABLED(proto, TLS_PROTO_TLS1_3)) {

	/* Use the generic method and constraint range after context is created */
	method = isServer ? TLS_server_method() : TLS_client_method();
	break;
#endif
    default:
	/* Negotiate highest available SSL/TLS version */
	method = isServer ? TLS_server_method() : TLS_client_method();
#if !defined(NO_TLS1) && !defined(OPENSSL_NO_TLS1) && !defined(OPENSSL_NO_TLS1_METHOD)
	off |= (ENABLED(proto, TLS_PROTO_TLS1)   ? 0 : SSL_OP_NO_TLSv1);
#endif
#if !defined(NO_TLS1_1) && !defined(OPENSSL_NO_TLS1_1) && !defined(OPENSSL_NO_TLS1_1_METHOD)
	off |= (ENABLED(proto, TLS_PROTO_TLS1_1) ? 0 : SSL_OP_NO_TLSv1_1);
#endif
#if !defined(NO_TLS1_2) && !defined(OPENSSL_NO_TLS1_2) && !defined(OPENSSL_NO_TLS1_2_METHOD)
	off |= (ENABLED(proto, TLS_PROTO_TLS1_2) ? 0 : SSL_OP_NO_TLSv1_2);
#endif
#if !defined(NO_TLS1_3) && !defined(OPENSSL_NO_TLS1_3)
	off |= (ENABLED(proto, TLS_PROTO_TLS1_3) ? 0 : SSL_OP_NO_TLSv1_3);
#endif
	break;
    }

#endif

    /* Force cipher selection order by server */
    if (!isServer) {
	SSL_CTX_set_options(ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
    }

    SSL_CTX_set_app_data(ctx, interp);	/* remember the interpreter */
    SSL_CTX_set_options(ctx, SSL_OP_ALL);	/* all SSL bug workarounds */
    SSL_CTX_set_options(ctx, SSL_OP_NO_COMPRESSION);	/* disable compression even if supported */
    SSL_CTX_set_options(ctx, off);		/* disable protocol versions */
    SSL_CTX_sess_set_cache_size(ctx, 128);

    /* Set user defined ciphers, cipher suites, and security level */
    if ((ciphers != NULL) && !SSL_CTX_set_cipher_list(ctx, ciphers)) {

	    pkey = EVP_PKEY_new();
	    if (bne == NULL || rsa == NULL || pkey == NULL || !BN_set_word(bne,RSA_F4) ||
		!RSA_generate_key_ex(rsa, keysize, bne, NULL) || !EVP_PKEY_assign_RSA(pkey, rsa)) {
		EVP_PKEY_free(pkey);
		/* RSA_free(rsa); freed by EVP_PKEY_free */
		BN_free(bne);
#else
	    pkey = EVP_RSA_gen((unsigned int)keysize);
	    ctx = EVP_PKEY_CTX_new(pkey,NULL);
	    if (pkey == NULL || ctx == NULL || !EVP_PKEY_keygen_init(ctx) ||
		!EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, keysize) || !EVP_PKEY_keygen(ctx, &pkey)) {
		EVP_PKEY_free(pkey);
		EVP_PKEY_CTX_free(ctx);
#endif
		Tcl_SetResult(interp,"Error generating private key",NULL);